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-   300 Whisper Rifles and Pistols (http://www.quarterbore.net/forums/forumdisplay.php?f=37)
-   -   Anyone running a 7in barrel on their ar15? (http://www.quarterbore.net/forums/showthread.php?t=3768)

Spook 07-11-2010 08:59 PM

couldnt resist
 
http://usera.ImageCave.com/Spook/1bullethose.jpg
I couldnt resist so I spun one up this afternoon...8.5",8T, set up for a .940 gasblock...It'll probably end up reamed to 308 X 39 but in either case it'll be a hose. Left it heavy to discourage muzzle climb.

JFettig 07-12-2010 08:43 PM

Looks good Spook,

Keep in mind that the shorter gas system is probably not optimal for supersonic high pressure rounds, I haven't run quickload on it but I bet it would have too high of pressures.

Jon

Spook 07-13-2010 07:09 PM

Jon/mak, Had it out today with 220 rn's over 9 gr VVN 110...ran like a sewing machine...the accuracy was right in there with the 10.5", which was about what I had figured.

Is this the evolution of the whisper barrel?

mak91 07-13-2010 08:52 PM

Nice work Spook. That high mount upper is my favorite for optics.

JFettig 07-13-2010 08:52 PM

I think it is an evolution, not being able to shoot supersonic rounds will be a turn off for some. I'll be making up a fixture for making gas tubes soon.

Jon

Spook 07-13-2010 09:26 PM

You have to wonder if an adjustable gas block with a "low" setting for supersonic and a "hi" setting for subsonic......

Kind of the opposite for what it is when you use one for the pistol position?:smile:

JFettig 07-13-2010 10:56 PM

I didn't have much to go off of with quick load but it looks like pressures will be at least 1.5x on a 125gr bullet traveling 1600fps out of a 7" barrel.

I have a bunch of 160gr bullets that maybe I'll work up a load slowly, from 1000fps to as fast as I am comfortable with.

Spook, your labeling is backwards ;) even if it was pistol position the port would decrease for high velocity.


Jon

Spook 07-13-2010 11:16 PM

:grin: Jon ,you're right...must be AADD :o best get back on my meds.

mak91 07-14-2010 07:42 AM

Funny you guys would think about an adjustable gas block. I ordered one the other day for my 7 inch barrel. Its a PRI low profile adjustable gas block. I got this one because it is the exact size of the non adjustable one I have on it now so I should just have to pop out the gas tube I have already modified from the old one and use it on this one without any more mods.

JFettig 07-14-2010 08:53 AM

Now that I think about it some more, It should be feasable with an adjustable block but it might be finicky. I mean think about how finicky 5.56 is through a 7.5" barrel.

If all goes as planned, I'll be shooting some 165gr and more 220gr subs through my barrel tonight.

Jon


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